I built a site to browse which songs include samples of others. It's common in hip hop, electronic, pop, etc to reuse drum breaks, melodies, or vocal snippets of other tracks. SampleBrainz includes 220,000+ of these connections.
All metadata is in the public domain (CC0), and anyone can contribute by adding sample relationships on MusicBrainz.
Source code at https://github.com/AndrewBelt/SampleBrainz
